-LRB- CNN -RRB- -- A major international environmental group has pulled out of the process to guarantee that diamonds do not come from conflict zones , saying the Kimberley Process had refused `` to evolve and address the clear links between diamonds , violence and tyranny . '' So why are so-called `` conflict diamonds '' so controversial ?

What are conflict diamonds ?

Conflict or `` blood '' diamonds are illegally traded to fund conflict in war-torn areas , particularly in central and western Africa , according to the World Diamond council , which represents the commercial diamond trade .

The United Nations defines conflict diamonds as '' ... diamonds that originate from areas controlled by forces or factions opposed to legitimate and internationally recognized governments , and are used to fund military action in opposition to those governments , or in contravention of the decisions of the Security Council . ''

They are generally in `` rough '' form , meaning they have recently been extracted and not yet cut .

At the height of the civil war in Sierra Leone , it is estimated that conflict diamonds represented approximately four percent of the world 's diamond production .

Who suffers ?

Apart from the innocent people caught up in the conflicts that the trade fuels , thousands of men , women and children in countries such as Sierra Leone are used as slaves to extract diamonds . They are often forced to use primitive , back-breaking methods such as digging into mud or gravel along river banks with their bare hands . The collected material is then separated using hand-held sieves .

What is the Kimberley Process ?

The Kimberley Process started when Southern African diamond-producing states met in Kimberley , South Africa , in May 2000 , to discuss ways to stop the trade in conflict diamonds and ensure that diamond purchases were not funding violence .

The result was an agreement by the United Nations , European Union , the governments of 74 countries , the World Diamond Council -- representing the industry -- and a number of interest groups such as Global Witness .

They established the Kimberley Process Certification Scheme -LRB- KPCS -RRB- , whereby members are required to certify that all rough diamond exports are produced through legitimate mining and sales activities and are `` conflict-free . ''

Each shipment carries a certificate that details where the diamonds came from , how they were mined , where they were cut and polished , the parties involved , and their ultimate destination . The idea is that members of the Kimberley Process can not trade with non-members .

Is it working ?

According to Amy Barry of Global Witness , the Kimberley Process has yet to demonstrate itself capable of stopping the trade because of a lack of political will among member states .

`` Zimbabwe , for example , is a test case for the KP , '' she told CNN in 2010 , alleging that Robert Mugabe 's regime has benefited from the sale of blood diamonds despite it being a member of the Kimberley Process .

She said the huge Marange diamond fields of eastern Zimbabwe are operated by military-run syndicates who beat or kill miners who do n't mine for them or pay bribes . The extreme violence perpetrated by the military even included the mass murder of hundreds of miners by helicopter gunships , she added .

But with just one or two member states able to veto any punitive action against abuses or infringements of the KP scheme , no decisive action has been taken against Zimbabwe . `` This consensus decision-making means tough decisions do n't get made , '' said Barry . `` Certain countries are putting economic and political interests in front of defending the fundamental principles of the scheme . ''

Is the `` conflict trade '' limited to diamonds ?

No . According to Global Witness , rebel fighters and army units have hijacked the trade in mineral ores , used in the production of mobile phones and computers , from eastern Democratic Republic of Congo -LRB- DRC -RRB- , while subjecting the local population to massacres , rape , extortion , and forced labor .

The `` conflict minerals '' are then laundered into the global supply chain by export houses , before being transformed into refined metals by large international smelting firms . Global Witness says the operations of some of the world 's leading consumer brands are now being scrutinized for evidence of links to this rogue trade .

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Group pulls out of process to guarantee diamonds do not come from conflict zones

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Conflict or `` blood '' diamonds are illegally traded to fund conflict in war-torn areas

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Thousands in countries such as Sierra Leone are used as slaves to extract diamonds

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Global Witness : Kimberley Process has not shown itself capable of stopping trade